Copper alloy sputtering target and method for manufacturing the target

A copper alloy sputtering target most suitable for formation of an interconnection material of a semiconductor device, particularly for formation of a seed layer, characterized in that the target contains 0.4 to 5 wt % of Sn, and the structure of the target does not substantially contain any precipitates, and the resistivity of the target material is 2.2 μΩcm or more. This target enables formation of an interconnection material of a semiconductor device, particularly a uniform seed layer stable during copper electroplating and is excellent in sputtering deposition characteristics. A method for manufacturing such a target is also disclosed.

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Description
BACKGROUND OF THE INVENTION

The present invention pertains to a copper alloy sputtering target capable of forming an interconnection material of a semiconductor device, particularly a stable and even seed layer during electroplating, and superior in sputtering deposition characteristics. The present invention also pertains to the manufacturing method of such a target.

Conventionally, although Al (resistivity of roughly 3.1 μΩ·cm) has been used as the interconnection material of a semiconductor device, low-resistivity copper interconnection (resistivity of roughly 1.7 μΩ·cm) has been put into practical application pursuant to the miniaturization of wiring.

As the current formation process of copper interconnection, after forming a diffusion barrier layer such as Ta/TaN to the concave portion of a contact hole or wiring groove, copper electroplating is often performed thereto. As the base layer (seed layer) for performing this electroplating, sputtering deposition is generally performed to copper or copper alloy.

The even formation of this base layer is important, and, if the base layer agglomerares, an even film cannot be formed upon forming a copper film with electroplating. For instance, defects such as voids, hillocks, disconnections and so on may be formed during the wiring.

Further, even if defects such as a void are not formed, an uneven copper electrodeposit will be formed at this portion, and a problem will arise in that the electromigration resistance characteristics will deteriorate.

In order to overcome this problem, it is important to form a stable and even seed layer during copper electroplating, and a sputtering target having superior sputtering deposition characteristics and being optimum for forming a seed layer will be required therefor.

Heretofore, as the copper interconnection material, a proposal has been made of adding certain elements to copper so as to improve the electromigration (EM) resistance characteristics, corrosion resistance, bond strength, and so on. For example, Japanese Patent Laid-Open Publication No. H5-311424 and Japanese Patent Laid-Open Publication No. H10-60633 disclose a pure copper target or a target to which 0.04 to 0.15 wt % of Ti is added to the pure copper.

And, in these proposals, it is proposed that rapid cooling be performed for the even dispersion of the added elements, or continuous casting be performed for preventing the segregation of the added elements in an ingot, ingot piping during casting, or enlargement of the crystal grains of the ingot.

Nevertheless, even if high purity copper is used alone or with minute amounts of metal added thereto, although there is an advantage in that the resistivity will be low, problems regarding electromigration and oxidation resistance during the process still remain, and these materials are not necessarily favorable materials.

In particular, since the aspect ratio is becoming higher (aspect ratio of 4 or higher) in recent days, sufficient electromigration resistance and oxidation resistance are required.

In light of the above, although a copper alloy sputtering target formed from high purity copper or with certain elements added thereto has been proposed, conventionally, this was not exactly sufficient.

Accordingly, an object of the present invention is to provide a copper alloy sputtering target capable of forming an interconnection material of a semiconductor device, particularly a stable and even seed layer during electroplating, and superior in sputtering deposition characteristics. Another object of the present invention is to provide a manufacturing method of such a target.

SUMMARY OF THE INVENTION

In order to achieve the foregoing objects, as a result of conducting intense study, the present inventors have discovered that, as a result of adding a suitable amount of metal elements, it is possible to obtain a copper alloy sputtering target capable of preventing the generation of defects such as voids, hillocks and disconnections during copper electroplating, which has low resistivity, which has electromigration resistance and oxidization resistance characteristics, and which is able to form a stable and even seed layer.

Based on the foregoing discovery, the present invention provides:

  • 1. A copper alloy sputtering target most suitable for formation of an interconnection material of a semiconductor device, particularly for formation of a seed layer, wherein said target contains 0.4 to 5 wt % of Sn, the structure of the target does not substantially contain any precipitates, and the resistivity of the target material is 2.3 μΩcm or more;
  • 2. A copper alloy sputtering target according to paragraph 1 above, wherein said target contains 0.5 to 1 wt % of Sn;
  • 3. A copper alloy sputtering target most suitable for formation of an interconnection material of a semiconductor device, particularly for formation of a seed layer, wherein said target contains 0.2 to 5 wt % of Al, the structure of the target does not substantially contain any precipitates, and the resistivity of the target material is 2.2 μΩcm or more;
  • 4. A copper alloy sputtering target according to paragraph 3 above, wherein said target contains 0.5 to 1 wt % of Al;
  • 5. A copper alloy sputtering target most suitable for formation of an interconnection material of a semiconductor device, particularly for formation of a seed layer, wherein said target contains 0.3 to 5 wt % of Ti, the structure of the target does not substantially contain any precipitates, and the resistivity of the target material is 9 μΩcm or more;
  • 6. A copper alloy sputtering target according to paragraph 5 above, wherein said target contains 0.5 to 1 wt % of Ti;
  • 7. A copper alloy sputtering target most suitable for formation of an interconnection material of a semiconductor device, particularly for formation of a seed layer, wherein said target contains a total of 0.2 to 5 wt % of at least one component selected from Sn, Al and Ti, the structure of the target does not substantially contain any precipitates, and the resistivity of the target material is greater than the resistivity of the copper alloy having the same composition in a thermal equilibrium state;
  • 8. A copper alloy sputtering target according to paragraph 7 above, wherein said target contains a total of 0.5 to 1 wt % of at least one component selected from Sn, Al and Ti;
  • 9. A copper alloy sputtering target according to paragraph 7 or paragraph 8, wherein the increase in resistivity due to the alloying element is resistivity that is 1.2 times or more than that of the thermal equilibrium;
  • 10. A copper alloy sputtering target according to any one of paragraphs 1 to 9 above, wherein Na and K are respectively 0.5 ppm or less; Fe, Ni, Cr and Ca are respectively 2 ppm or less; U and Th are respectively 1 ppb or less, oxygen is 5 ppm or less, hydrogen is 2 ppm or less; and unavoidable impurities excluding alloying additional elements are 50 ppm or less;
  • 11. A copper alloy sputtering target according to any one of paragraphs 1 to 9 above, wherein Na and K are respectively 0.1 ppm or less; Fe, Ni, Cr and Ca are respectively 1 ppm or less; U and Th are respectively 1 ppb or less, oxygen is 5 ppm or less, hydrogen is 2 ppm or less; and unavoidable impurities excluding alloying additional elements are 10 ppm or less;
  • 12. A copper alloy sputtering target according to any one of paragraphs 1 to 11 above, wherein the crystal grain size of the target material is 50 μm or less, and the variation in the average grain size by location is within ±20%;
  • 13. A copper alloy sputtering target according to any one of paragraphs 1 to 12 above, wherein the variation in the alloying element of the target material within 0.2%;
  • 14. A copper alloy sputtering target according to any one of paragraphs 1 to 13 above, wherein, when the alloy contains Al, the ratio I(111)/I(200) of the X-ray diffraction peak intensity I(111) of the (111) face and the X-ray diffraction peak intensity I(200) of the (200) face is 2.2 or more in the sputtering face, and, when the alloy contains Sn and/or Ti, the ratio I(111)/I(200) of the X-ray diffraction peak intensity I(111) of the (111) face and the X-ray diffraction peak intensity I(200) of the (200) face is 2.2 or less in the sputtering face, and the variation in I(111)/I(200) in the sputtering face is respectively within ±30%; and
  • 15. A manufacturing method of a copper alloy sputtering target according to any one of paragraphs 1 to 14 above, comprising the steps of performing hot forging and/or hot rolling to a high purity copper alloy ingot obtained by vacuum melting; further performing cold rolling thereto; and thereafter sandwiching this with copper plates underwater and performing forced cooling thereto during heat treatment.

DETAILED DESCRIPTION OF THE INVENTION

The copper alloy sputtering target of the present invention contains a 0.4 to 5 wt %, preferably 0.5 to 1 wt % of Sn; 0.2 to 5 wt %, preferably 0.5 to 1 wt % of Al; 0.3 to 5 wt %, preferably 0.5 to 1 wt % of Ti; respectively, or a total of 0.2 to 5 wt % of at least one component selected from Sn, Al and Ti.

When 0.4 to 5 wt % of Sn is independently added, resistivity of the target material will be 2.3 μΩcm or more; when 0.2 to 5 wt % of Al is independently added, resistivity of the target material will be 2.2 μΩcm or more, and when 0.3 to 5 wt % of Ti is independently added, resistivity of the target material will be 9 μΩcm or more. Further, when these are mixed and added, resistivity of the target material will be 2.2 μΩcm or more. These may be suitably selected and used for the formation of a seed layer during copper electroplating.

Although the structure of the copper alloy sputtering target of the present invention does not substantially contain any precipitates, when the foregoing additive amount of alloy exceeds 5 wt %, precipitates will arise during the manufacture process of the target.

When precipitates exist in the target structure, particles will be generated since the sputtering rate between the matrix phase and precipitate phase will differ, and problems such as wiring disconnections in the semiconductor device will occur.

In particular, it has become evident that these precipitates are formed in the center (middle) of the target separate from the surface, and not near the target surface.

Therefore, problems caused by precipitates occur not during the initial phase of sputtering, but from a stage in which the erosion of the target caused by sputtering has progressed to a certain degree. In other words, precipitates are caused by minute particles getting mixed into the sputtering film, or due to the micro unevenness of the film composition midway during sputtering.

As a matter of course, since such uneven portions of the seed film generate uneven electric fields, the copper plating film structure will become uneven and minute, and electromigration resistance characteristics will deteriorate, which is obviously unfavorable. Although the problem is often overlooked since it does not occur in the initial stages, this is a major problem.

In light of the above, in order to confirm the existence of precipitates in the target, it is insufficient to search only the mechanical strength characteristics such as the resistivity value and hardness of the target surface with the likes of XRD, and it is necessary to also search the inside of the target with high resolution SEM.

Further, with the copper alloy sputtering target of the present invention, it is desirable that Na and K are respectively 0.5 ppm or less, preferably 0.1 ppm or less; Fe, Ni, Cr and Ca are respectively 2 ppm or less, preferably 1 ppm or less; U and Th are respectively 1 ppb or less, oxygen is 5 ppm or less, hydrogen is 2 ppm or less; and unavoidable impurities excluding alloying additional elements are 50 ppm or less. These elements are harmful components that may diffuse and contaminate the semiconductor device.

It is preferable that the crystal grain size of the target material is 50 μm or less, and the variation in the average grain size by location is within ±20%. The crystal grain size of the target and variations in the average grain size by location will affect the uniformity of the film thickness.

Moreover, when the variation is significant in the alloy elements of the target material, the characteristic values of the target material will change and therefore cause the interconnection material of the semiconductor device, particularly the resistivity of the seed layer, to change, and it is desirable that the variation be within 0.2%.

Further, orientation of the crystal will also affect the uniformity of the film thickness. Generally, although it is considered that a random orientation is favorable, depending on the type of additive element, a specific crystal orientation with the variation being within a certain range will yield a further superior uniformity of the film thickness.

In other words, when the alloy contains Al, the ratio I(111)/I(200) of the X-ray diffraction peak intensity I(111) of the (111) face and the X-ray diffraction peak intensity I (200) of the (200) face is 2.2 or more in the sputtering face, and, when the alloy contains Sn and/or Ti, the ratio I(111)/I(200) of the X-ray diffraction peak intensity I(111) of the (111) face and the X-ray diffraction peak intensity I(200) of the (200) face is 2.2 or less in the sputtering face. And, when the variation in I(111)/I(200) in the sputtering face is respectively within ±30%, the film thickness standard deviation σ will be 1.5% or less, and a copper alloy sputtering target superior in uniformity of the film thickness can be obtained thereby.

Further, upon manufacturing the target, after performing homogenization heat treatment with a certain degree of thickness, in the subsequent cooling step, it is important to sandwich this with metals having a large thermal capacity such as copper plates underwater, and to increase the cooling effect without generating a vapor layer on the surface thereof. This is because if a vapor layer is formed, the cooling effect will significantly deteriorate.

EXAMPLES AND COMPARATIVE EXAMPLES

The present invention is now explained in detail with reference to the Examples. These Examples are merely illustrative, and the present invention shall in no way be limited thereby. In other words, various modifications and other embodiments based on the technical spirit claimed in the claims shall be included in the present invention as a matter of course.

Example 1-1

Electrolytic copper (purity of 99.95%) was subject to electrolytic refining in nitric solution so as to differentiate anodes from cathodes with a diaphragm such that it became a purity of 99.9999%. 1.0 wt % of Sn (purity of 99.9999%) was added thereto, and this was subject to vacuum melting in order to prepare a high purity copper alloy ingot (φ 160×60t) containing 1.0 wt % of Sn.

This ingot was heated to 400° C. and subject to hot forging such that it became φ 190×40t. Further, this was heated to 400° C. and rolled until it became φ 265×20t. Thereafter, this was rolled until it became φ 360×10t with cold rolling, heat treatment was performed thereto at 500° C. for 1 hour, and this was sandwiched with copper plates under water for forced cooling.

Moreover, this was machine processed to obtain a discoid target having a diameter of 13 inches and a thickness of 7 mm.

Example 1-2

Electrolytic copper (purity of 99.95%) was subject to electrolytic refining in nitric solution so as to differentiate anodes from cathodes with a diaphragm such that it became a purity of 99.9999%. 0.5 wt % of Sn (purity of 99.9999%) was added thereto, and this was subject to vacuum melting in order to prepare a high purity copper alloy ingot (φ 160×60t) containing 0.5 wt % of Sn.

With the other conditions being the same as Example 1-1, a copper alloy target containing 0.5 wt % of Sn was prepared.

Comparative Example 1-1

Using the same materials as Example 1-1, after performing heat treatment at 500 degrees for 1 hour, this was cooled in a furnace. The other conditions were the same as Example 1-1. As a result, a copper alloy target containing 1.0 wt % of Sn was prepared.

Comparative Example 1-2

Using the same materials as Example 1-2, after performing heat treatment at 500 degrees for 1 hour, this was cooled in a furnace. The other conditions were the same as Example 1-2. As a result, a copper alloy target containing 0.5 wt % of Sn was prepared.

Example 2-1

Electrolytic copper (purity of 99.95%) was subject to electrolytic refining in nitric solution so as to differentiate anodes from cathodes with a diaphragm such that it became a purity of 99.9999%. 1.0 wt % of Al (purity of 99.9999%) was added thereto, and this was subject to vacuum melting in order to prepare a high purity copper alloy ingot (φ 160×60t) containing 1.0 wt % of Al.

This ingot was heated to 400° C. and subject to hot forging such that it became φ 190×40t. Further, this was heated to 400° C. and rolled until it became φ 265×20t.

Thereafter, this was rolled until it became φ 360×10t with cold rolling, heat treatment was performed thereto at 500° C. for 1 hour, and this was sandwiched with copper plates under water for forced cooling. Moreover, this was machine processed to obtain a discoid target having a diameter of 13 inches and a thickness of 7 mm.

Example 2-2

Electrolytic copper (purity of 99.95%) was subject to electrolytic refining in nitric solution so as to differentiate anodes from cathodes with a diaphragm such that it became a purity of 99.9999%. 0.5 wt % of Al (purity of 99.9999%) was added thereto, and this was subject to vacuum melting in order to prepare a high purity copper alloy ingot (φ 160×60t) containing 0.5 wt % of Al.

With the other conditions being the same as Example 2-1, a copper alloy target containing 0.5 wt % of Al was prepared.

Comparative Example 2-1

Using the same materials as Example 2-1, after performing heat treatment at 500 degrees for 1 hour, this was cooled in a furnace. The other conditions were the same as Example 2-1. As a result, a copper alloy target containing 1.0 wt % of Al was prepared.

Comparative Example 2-2

Using the same materials as Example 2-2, after performing heat treatment at 500 degrees for 1 hour, this was cooled in a furnace. The other conditions were the same as Example 2-2. As a result, a copper alloy target containing 0.5 wt % of Al was prepared.

Example 3-1

Electrolytic copper (purity of 99.95%) was subject to electrolytic refining in nitric solution so as to differentiate anodes from cathodes with a diaphragm such that it became a purity of 99.9999%. 1.0 wt % of Ti (purity of 99.9999%) was added thereto, and this was subject to vacuum melting in order to prepare a high purity copper alloy ingot (φ 160×60t) containing 1.0 wt % of Ti.

This ingot was heated to 400° C. and subject to hot forging such that it became φ 190×40t. Further, this was heated to 400° C. and rolled until it became φ 265×20t. Thereafter, this was rolled until it became φ 360×10t with cold rolling, heat treatment was performed thereto at 500° C. for 1 hour, and this was sandwiched with copper plates under water for forced cooling.

Moreover, this was machine processed to obtain a discoid target having a diameter of 13 inches and a thickness of 7 mm.

Example 3-2

Electrolytic copper (purity of 99.95%) was subject to electrolytic refining in nitric solution so as to differentiate anodes from cathodes with a diaphragm such that it became a purity of 99.9999%. 0.5 wt % of Ti (purity of 99.9999%) was added thereto, and this was subject to vacuum melting in order to prepare a high purity copper alloy ingot (φ 160×60t) containing 0.5 wt % of Ti.

With the other conditions being the same as Example 3-1, a copper alloy target containing 0.5 wt % of Ti was prepared.

Comparative Example 3-1

Using the same materials as Example 3-1, after performing heat treatment at 500 degrees for 1 hour, this was cooled in a furnace. The other conditions were the same as Example 3-1. As a result, a copper alloy target containing 1.0 wt % of Ti was prepared.

Comparative Example 3-2

Using the same materials as Example 3-2, after performing heat treatment at 500 degrees for 1 hour, this was cooled in a furnace. The other conditions were the same as Example 3-2. As a result, a copper alloy target containing 0.5 wt % of Ti was prepared.

Evaluation Results of Examples 1-1 to 3-2 and Comparative Examples 1-1 to 3-2

With respect to the targets prepared in foregoing Examples 1-1 to 3-2 and Comparative Examples 1-1 to 3-2, measurement, observation, research and so on regarding the resistivity (μΩ·cm), precipitates, crystal grain size, variation, existence of voids, hillocks and disconnections were conducted. The results are shown in Table 1. Further, the analysis results of impurities of the targets are shown in Table 2.

Further, the crystal grain size was calculated with the method of section prescribed in JIS H0501, and the variation was calculated by radially measuring 17 points (center, and 8 points of 1/2R and 8 points of R) of the sputtering face of the target. Moreover, the existence of precipitates was searched with high resolution SEM.

The resistivity was calculated by measuring 17 points, respectively, in the upper face, lower face and middle face of the target with the four-terminal method. Regarding the EM characteristics evaluation, after depositing a Ta/TaN diffusion barrier to a wiring groove having a wiring width of 0.2 μm and depth of 0.8 μm, a copper alloy seed film of 500 Å (deposition film thickness on a flat substrate) was formed on each of the various targets described above. Thereafter, with copper containing phosphorus as the anode, a copper film was embedded with the electroplating method, and excess film at the upper part was removed with the CMP method. Thereafter, annealing was performed at 400° C. in an Ar gas atmosphere, current having a current density of 1012/ampere was applied to the wiring net for 1 hour in order to observe the existence of voids and hillocks in the wiring as electromigration (EM) characteristics.

Further, the ratio I(111)/I(200) of the X-ray diffraction peak intensity I(111) of the (111) face and the X-ray diffraction peak intensity I(200) of the (200) face which corresponds to Example 1-1 and Example 1-2 is shown in Table 3, the ratio of I(111)/I(200) corresponding to Example 2-1 and Example 2-2 is shown in Table 4, and the ratio of I(111)/I(200) corresponding to Examples 3-1 and Example 3-2 is shown in Table 5, respectively.

Moreover, the influence (film thickness standard deviation σ(%)) of the ratio I(111)/I(200) with the X-ray diffraction peak intensity I(200) on the film thickness distribution is shown in Table 6. Here, the variation of I(111)/I(200) in the sputtering face was all within ±30%.

As a comparison, Comparative Examples 1-1 to 3-4 are also shown. Comparative Examples 2-3 and 2-4 are targets in which the final heat treatment was not performed, and Comparative Examples 1-3, 1-4, 3-3 and 3-4 are cases where the heat treatment temperature was set to 750° C. for 1 hour.

TABLE 1 Resistivity Grain Size Variation Existence Existence Target (μΩ · cm) Precipitates (μm) (±%) of Voids of Hillocks Disconnections Examples 1-1 Cu + 1.0% Sn 3.3 Not Observed 23 15 None None None Comparative Cu + 1.0% Sn 2.7 Small Amount 68 26 Existed Existed None Examples 1-1 Examples 1-2 Cu + 0.5% Sn 2.5 Not Observed 22 11 None None None Comparative Cu + 0.5% Sn 2.1 Small Amount 48 12 Existed Existed Existed Examples 1-2 Examples 2-1 Cu + 1.0% Al 4.3 Not Observed 39 11 None None None Comparative Cu + 1.0% Al 3.8 Small Amount 85 34 Existed Existed None Examples 2-1 Examples 2-2 Cu + 0.5% Al 2.8 Not Observed 45 19 None None None Comparative Cu + 0.5% Al 2.2 Small Amount 95 42 Existed Existed None Examples 2-2 Examples 3-1 Cu + 1.0% Ti 15.1 Not Observed 29 13 None None None Comparative Cu + 1.0% Ti 12.6 Small Amount 58 18 Existed Existed Existed Examples 3-1 Examples 3-2 Cu + 0.5% Ti 13.2 Not Observed 36 9 None None None Comparative Cu + 0.5% Ti 10.5 Small Amount 41 26 Existed Existed None Examples 3-2

TABLE 2 Example 1-1 Comparative Example 1-1 Example 1-2 Comparative Example 1-2 Example 2-1 Comparative Example 2-1 Sn — — — — 0.01 0.01 Al 0.03 0.03 0.02 0.02 — — Ti 0.03 0.03 0.03 0.03 0.03 0.03 Na 0.01 0.01 0.01 0.01 0.01 0.01 K 0.01 0.01 0.02 0.02 0.01 0.01 Fe 0.08 0.08 0.09 0.09 0.02 0.02 Ni 0.06 0.06 0.05 0.05 0.008 0.008 Cr 0.04 0.04 0.04 0.04 0.005 0.005 Ca 0.01 0.01 0.01 0.01 0.005 0.005 C 10 10 8 8 10 10 O 10 10 7 7 10 10 H 1 1 1 1 1 1 Ag 0.27 0.27 0.23 0.23 0.3 0.3 Zr 0.005 0.005 0.005 0.005 0.01 0.01 Hf 0.001 0.001 0.001 0.001 0.001 0.001 U 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 Th 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 Example 2-2 Comparative Example 2-2 Example 3-1 Comparative Example 3-1 Example 3-2 Comparative Example 3-2 Sn 0.02 0.02 0.04 0.04 0.04 0.04 Al — — 0.13 0.13 0.11 0.11 Ti 0.01 0.01 — — — — Na 0.01 0.01 0.01 0.01 0.01 0.01 K 0.01 0.01 0.01 0.01 0.01 0.01 Fe 0.03 0.03 0.1 0.1 0.1 0.1 Ni 0.01 0.01 0.03 0.03 0.05 0.05 Cr 0.004 0.004 0.03 0.03 0.01 0.01 Ca 0.003 0.003 0.05 0.05 0.03 0.03 C 9 9 10 10 8 8 O 8 8 10 10 9 9 H 1 1 1 1 1 1 Ag 0.23 0.23 0.33 0.33 0.22 0.22 Zr 0.02 0.02 0.01 0.01 0.01 0.01 Hf 0.001 0.001 0.001 0.001 0.001 0.001 U 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 Th 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001

TABLE 3 Cu-1 wt % Sn (Corresponds to Example 1-1) 1 2 3 4 5 6 7 8 9 (111) 3602 3121 1782 2866 1971 2103 2866 2133 2966 (200) 1915 1469 1347 1538 1422 1137 1255 1194 1499 (220) 591 727 1024 587 982 793 913 608 816 (311) 794 725 728 680 569 733 683 591 709 (111)/(200) 1.88 2.12 1.32 1.86 1.39 1.85 2.28 1.79 1.98 Cu-0.5 wt % Sn (Corresponds to Example 1-2) 1 2 3 4 5 6 7 8 9 (111) 3510 2960 1586 2768 2709 2814 2696 2812 2613 (200) 1924 1528 1354 1643 1647 1598 1637 1635 1621 (220) 623 745 1031 602 601 587 587 560 593 (311) 814 702 701 667 690 683 677 680 653 (111)/(200) 1.82 1.94 1.17 1.68 1.64 1.76 1.65 1.72 1.61

TABLE 4 Cu-0.5 wt % Al (Corresponds to Example 2-1) 1 2 3 4 4 4 4 4 4 (111) 21421 16109 17788 24298 24298 24298 24298 24298 24298 (200) 9024 8697 7570 8466 8466 8466 8466 8466 8466 (220) 3107 5249 3713 2850 2850 2850 2850 2850 2850 (311) 3970 3266 3690 3700 3700 3700 3700 3700 3700 (111)/(200) 2.37 1.85 2.35 2.87 2.87 2.87 2.87 2.87 2.87 Cu-1 wt % Al (Corresponds to Example 2-2) 1 2 3 4 5 6 7 8 9 (111) 29341 27830 26552 30444 22078 25913 25215 26319 31025 (200) 12085 11620 11271 12027 13537 12550 13131 11388 12027 (220) 10458 11330 14816 9528 15687 14176 14525 14467 9703 (311) 6217 7321 5520 6101 6798 5403 5229 5926 5345 (111)/(200) 2.43 2.40 2.36 2.53 1.63 2.06 1.92 2.31 2.58

TABLE 5 Cu-1 wt % Ti (Corresponds to Example 3-1) 1 2 3 4 5 6 7 8 9 (111) 2466 3184 1548 2786 2963 3022 1638 2677 2997 (200) 1757 1652 1123 1780 1866 1542 1213 1643 1466 (220) 690 520 1129 513 613 513 544 498 533 (311) 666 709 586 684 658 684 711 644 703 (111)/(200) 1.40 1.93 1.38 1.57 1.59 1.96 1.35 1.63 2.04 Cu-0.5 wt % Ti (Corresponds to Example 3-2) 1 2 3 4 5 6 7 8 9 (111) 2176 3140 1505 2671 2666 2863 1335 2401 2939 (200) 1770 1689 1157 1847 1873 1552 1274 1672 1474 (220) 713 528 1125 512 632 514 546 460 534 (311) 635 720 585 694 672 685 680 641 703 (111)/(200) 1.23 1.86 1.30 1.45 1.42 1.85 1.05 1.44 1.99

TABLE 6 Comparative Comparative Cu—Sn Example 1-1 Example 1-2 Example 1-3 Example 1-4 (111)/(200) 1.83 1.67 2.35 3.56 Film Thickness 1.5 1.1 1.7 1.9 standard deviation σ (%) Comparative Comparative Cu—Al Example 2-1 Example 2-2 Example 2-3 Example 2-4 (111)/(200) 2.64 2.25 1.73 1.21 Film Thickness 1.3 1.4 1.8 2.6 standard deviation σ (%) Comparative Comparative Cu—Ti Example 3-1 Example 3-2 Example 3-3 Example 3-4 (111)/(200) 1.65 1.51 2.74 3.46 Film Thickness 1.2 1 1.8 2.3 standard deviation σ (%)

As clear from Table 1, regarding Examples 1-1 to 3-2, precipitates were not observed, the crystal grain size was within the range of 50 μm, the variation was minor, voids and hillocks did not exist, and there were no disconnections.

Contrarily, regarding Comparative Examples 1-1 to 3-2, precipitates were observed, the crystal grain size enlarged, the variation was significant, voids and hillocks existed, and there were disconnections. The results were all inferior in comparison to Examples 1-1 to 3-2.

Further, as shown in Tables 3 to 6, when the alloy contained Al, the ratio I(111)/I(200) of the X-ray diffraction peak intensity I(111) of the (111) face and the X-ray diffraction peak intensity I(200) of the (200) face was 2.2 or more in the sputtering face, and, when the alloy contained Sn and/or Ti, the ratio I(111)/I(200) of the X-ray diffraction peak intensity I(111) of the (111) face and the X-ray diffraction peak intensity I(200) of the (200) face was 2.2 or less in the sputtering face, the film thickness standard deviation σ was 1.5% or less, and a copper alloy sputtering target having superior evenness in film thickness was obtained thereby. Contrarily, in Comparative Examples 1-3, 1-4, 2-3, 2-4, 3-3 and 3-4, σ exceeded 1.5% in all cases, and resulted in inferior evenness.

Accordingly, it is evident that the copper alloy sputtering target of the present invention possesses favorable characteristics.

The copper alloy sputtering target of the present invention yields superior effects in that it is capable of preventing the generation of defects such as voids, hillocks and disconnections during copper electroplating, it has low resistivity, it has electromigration resistance and oxidization resistance characteristics, and it is able to form a stable and even seed layer.

Claims

1. A sputtering target for forming a seed layer of a semiconductor device, comprising: a copper alloy sputtering target containing 0.2 to 5 wt % of Al and having a sputtering face, said target having a resistivity of 2.2 μΩcm or more and an average crystal grain size of 50 μm or less, said target having a ratio I(111)/(200) of an X-ray diffraction peak intensity I(111) of a (111) face and an X-ray diffraction peak intensity I(200) of a (200) face of 2.2 or more in said sputtering face, and variation in I(111)/I(200) in said sputtering face is respectively within ±30%.

2. A copper alloy sputtering target according to claim 1, wherein said target contains 0.5 to 1 wt % of Al.

3. A sputtering target for forming a seed layer of a semiconductor device, comprising: a copper alloy sputtering target containing 0.2 to 5 wt % of an alloying component of Al and having a sputtering face, said target having a resistivity of greater than a resistivity of a copper alloy having the same composition in a thermal equilibrium state and an average crystal grain size of 50 μm or less, wherein a ratio I(111)/I(200) of an X-ray diffraction peak intensity I(111) of a (111) face and an X-ray diffraction peak intensity I(200) of a (200) face is 2.2 or more in said sputtering face, and variation in I(111)/I(200) in said sputtering face is respectively within ±30%.

4. A copper alloy sputtering target according to claim 3, wherein said target contains a total of 0.5 to 1 wt % of Al.

5. A copper alloy sputtering target according to claim 3, wherein an increase in resistivity due to said alloying component in said target is 1.2 times or more than that of said copper alloy in said thermal equilibrium state.

6. A copper alloy sputtering target according to claim 3, wherein variation in average grain size by location is within ±20%.

7. A copper alloy sputtering target according to claim 3, wherein variation in the content of said alloying component of Al by location in said target is within 0.2%.

8. A copper alloy sputtering target according to claim 3, wherein each of Na and K contained within said target is 0.1 ppm or less; each of Fe, Ni, Cr and Ca contained within said target is 1 ppm or less; each of U and Th contained within said target is 1 ppb or less, oxygen contained in said target is 5 ppm or less, hydrogen contained in said target is 2 ppm or less; and unavoidable impurities excluding alloying elements are 10 ppm or less.

9. A copper alloy sputtering target according to claim 1, wherein each of Na and K contained within said target is 0.5 ppm or less; each of Fe, Ni, Cr and Ca contained within said target is 2 ppm or less; each of U and Th contained within said target is 1 ppb or less, oxygen contained in said target is 5 ppm or less, hydrogen contained in said target is 2 ppm or less; and unavoidable impurities excluding alloying elements are 50 ppm or less.

10. A copper alloy sputtering target according to claim 1, wherein variation in average grain size by location is within ±20%.

11. A copper alloy sputtering target according to claim 1, prepared by a process comprising the steps of:

obtaining a high purity copper alloy ingot by vacuum melting;
performing at least one of hot forging and hot rolling to said high purity copper alloy ingot;
thereafter, cold rolling said high purity copper alloy; and
thereafter sandwiching said high purity copper alloy with copper plates underwater and performing forced cooling thereto.

12. A copper alloy sputtering target for forming a seed layer of a semiconductor device, comprising:

a sputtering target body consisting of copper and 0.5 to 1 wt % of Al, said body having a sputtering face, an average crystal grain size of 50 μm or less, and a resistivity of 2.2 μΩcm or more;
said target having a ratio I(111)/I(200) of an X-ray diffraction peak intensity I(111) of a (111) face and an X-ray diffraction peak intensity I(200) of a (200) face of 2.2 or more in said sputtering face, and a variation in I(111)/I(200) in said sputtering face of respectively within ±30%.

13. A copper alloy sputtering target according to claim 12, wherein said resistivity of said sputtering target body is 2.8 to 4.3 μΩ·cm.

14. A copper alloy sputtering target according to claim 12, wherein said ratio I(111)/I(200) in said sputtering face is of 2.2 to 2.25.

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Patent History
Patent number: 9896745
Type: Grant
Filed: Dec 4, 2002
Date of Patent: Feb 20, 2018
Patent Publication Number: 20050121320
Assignee: JX Nippon Mining & Metals Corporation (Tokyo)
Inventors: Takeo Okabe (Ibaraki), Hirohito Miyashita (Ibaraki)
Primary Examiner: Keith Walker
Assistant Examiner: John A Hevey
Application Number: 10/501,117
Classifications
Current U.S. Class: Titanium, Zirconium, Or Hafnium Base (148/421)
International Classification: C22C 9/00 (20060101); C22C 9/01 (20060101); C22C 9/02 (20060101); C23C 14/34 (20060101); H01L 23/532 (20060101);